A process of manufacturing semiconductor substrates (hereinafter, simply referred to as “substrates”) conventionally involves various types of processing that is performed on substrates. For example, chemical solution processing such as etching is performed on a surface of a substrate having a resist pattern on the surface thereof, by supplying a chemical solution to the substrate. After the chemical solution processing has ended, cleaning processing is performed by supplying a cleaning liquid to the substrate, and then dry processing is performed on the substrate.
For example, Japanese Patent Application Laid-Open No. 2015-153947 (Document 1) proposes a substrate processing apparatus for processing substrates in an atmosphere where the oxygen concentration is low. The substrate processing apparatus includes a spin chunk that holds and rotates a substrate, a shielding member that is disposed over the substrate, and a cup that surrounds a spin base of the spin chunk. The shielding member has an opposed surface disposed over the substrate and an inner peripheral surface surrounding the substrate. The lower end of the inner peripheral surface of the shielding member is disposed in the periphery of the spin base.
The space between the upper surface of the substrate and the opposed surface of the shielding member is filled with an inert gas that is discharged from a discharge port of the shielding member. This reduces the oxygen concentration in an atmosphere that is in contact with the upper and outer peripheral surfaces of the substrate. The inert gas in the space between the substrate and the shielding member is drawn through the cup by suction by an exhaust unit provided at the bottom of the cup, flows into the cup from between the lower end of the inner peripheral surface of the shielding member and the outer peripheral surface of the spin base, and is exhausted to the outside of the cup.
In the substrate processing apparatus of Document 1, the distance in the radial direction between the cup upper end portion and the shielding member is less than the distance in the radial direction between the lower end of the inner peripheral surface of the shielding member and the outer peripheral surface of the spin base. By making small the ring-shaped clearance between the cup upper end portion and the shielding member in this way, it is possible to suppress the possibility that processing liquids dispersed from a rotating substrate into the cup may be dispersed through this clearance into the space above the cup.
Now, in the case where a plurality of types of processing liquids are sequentially supplied to a substrate and used to process the substrate, substrate processing apparatuses may separately recover or discard the processing liquids depending on the type of processing liquid. In this case, a plurality of cups may be disposed one inside another in the radial direction around the substrate, and the cups for receiving a processing liquid dispersed from the substrate may be switched by moving some of the cups in the up-down direction. For example, when a processing liquid is received by a radially outer cup, radially inward cups may be moved downward to place the radially outer cup around the substrate.
A case is assumed in which the substrate processing apparatus of Document 1 includes a plurality of cups and separate the aforementioned plurality of types of processing liquids. If a processing liquid is received by a radially outer cap, the small clearance between the cup upper end portion and the shielding member may increase the velocity of downflow of a gas that flows from the space over the cup into the cup through the clearance, and the processing liquid dispersed from the substrate into the cup may be caused to flow downward by the downflow of the gas. Consequently, the processing liquid that is supposed to be received by the radially outer cup may flow into a radially inner cup placed below the radially outer cup.